1. Field of the Invention
The invention relates to apparatus for spraying liquid using a manually operated spray pump.
2. Description of the Related Art
JP-A8-230,961 discloses a suction type spray device which is used in the state that the device is fitted to an opening of a neck portion of a container and which has a structure for spraying a liquid material inside the container.
Such a suction type spray device has a cylinder unit including an upper large-diameter air cylinder hung into the container and a small-diameter liquid cylinder continued to a lower side of the air cylinder and an operating member including a large-diameter cylindrical piston gas-tightly and slidably held at an inner peripheral face of the large-diameter air cylinder. The spray device also has a stem that is gas-tightly engaged in the small-diameter liquid cylinder, upwardly urged and extended upwardly from the liquid cylinder, gas-tightly passing a central hole of the air cylinder, and provided with a check valve at an upper inner side thereof. The operating member has a press-down head fitted with an upper portion of the stem, having a lower end portion of a peripheral wall connected to the large-diameter cylindrical piston and provided with a spray nozzle hole at a tip portion thereof, a liquid flow-out path for communicating the interior of the stem with the spray nozzle of the press-down head, and an air ejecting path communicating the air cylinder with the spray nozzle hole of the press-down head. When the operating member is pressed down, air is ejected through the ejecting nozzle hole to suck the liquid in the container and spray it.
In a conventional vertical spray device, the liquid is sprayed while being rotated at a high speed. However, according to the conventional spray unit, as the air is ejected at a high speed, a negative pressure is generated due to the high speed of the air. The suction is necessary to suck the liquid, mix it with the air and atomize the liquid. Therefore, this method is useful in that even a liquid having a relatively high viscosity is easily atomized, but there is a problem in that the mixture of air and liquid does not begin to spray until after air is continuously ejected for a while by pressing down the operating member, so that the start of the ejection of the liquid is delayed.
Although the factor which delays the start of the spraying of the air/fuel mixture is not clear, it is necessary that the air reaches a given high speed so as to suck out the liquid through the suction created by the air, and that a given time is required for the air speed to reach the high speed.